Using the interference of object light and reference light to record an interference pattern on photosensitive film, this interference pattern is a complex pattern with different transparency, which is called a hologram (that is, a hologram), which is equivalent to making the film into an irregular grating, and then extracting the original three-dimensional image by using the diffraction of appropriate illumination light by the hologram. The latter process is called reproduction. Hologram is a kind of natural information storage, which can "revive" the frozen scene in front of people. Because of this unique performance, holograms are widely used. Such as shock wave used to study rocket flight, nondestructive testing of honeycomb structure of aircraft wing, etc. Now there are not only laser holography, but also white light holography, rainbow holography and panoramic rainbow holography, so that people can see all sides of the scene. Holographic three-dimensional display is developing towards holographic color stereoscopic TV and movies.

In addition to using light waves to generate holograms, it has also developed into using computers to generate holograms. Holograms are widely used and can be made into various thin film optical elements, such as various lenses, gratings, filters, etc. , can overlap in space, very small and light, suitable for space flight. Using hologram to store data has the advantages of large capacity, easy extraction and pollution prevention.